Perhaps GotTheTshirt would know if Clare Roberts ever freelanced with Derby Airways - but I suspect she would be wearing slacks if piloting. At some stage she flew for Dan Air on their Ambassadors the first of which were introduced in 19559
Would Chrissair have been what we would now call a handling agent then, I doubt Luton had much other commercial traffic at that time. Before even my time - I would have been somewhere between three and five.